Implantable support device with graft

ABSTRACT

Implantable medical devices comprising a support frame and a graft member attached to the support frame. The support frame can define one or more structural features that substantially prevent migration of the graft member along the support frame.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.10/820,918, filed on Apr. 8, 2004, which claims priority to U.S.Provisional Application Ser. No. 60/461,339, filed on Apr. 8, 2003. Eachof these applications is hereby incorporated into this disclosure in itsentirety.

FIELD OF THE INVENTION

The invention relates to medical devices. More particularly, theinvention relates to intraluminal support devices with attached graftmembers. Exemplary embodiments of the invention relate to intraluminalprosthetic valves, such as prosthetic venous valves.

BACKGROUND OF THE INVENTION

Many vessels in animals transport fluids from one bodily location toanother. Frequently, fluid flows in a unidirectional manner along thelength of the vessel. Varying fluid pressures over time, however, canintroduce a reverse flow direction in the vessel. In some vessels, suchas mammalian veins, natural valves are positioned along the length ofthe vessel and act as one-way check valves that open to permit the flowof fluid in the desired direction, and quickly close upon a change inpressure, such as a transition from systole to diastole, to preventfluid flow in a reverse direction, i.e., retrograde flow. While thesenatural valves may function for an extended time, some may loseeffectiveness, which can lead to physical manifestations and pathology.For example, venous valves are susceptible to becoming insufficient dueto one or more of a variety of factors. Over time, the vessel wall maystretch, affecting the ability of the valve leaflets to close.Furthermore, the leaflets may become damaged, such as by formation ofthrombus and scar tissue, which may also affect the ability of the valveleaflets to close. Once valves are damaged, venous valve insufficiencyis present, and can lead to discomfort and possibly ulcers in the legsand ankles.

Current treatments for venous valve insufficiency include the use ofcompression stockings that are placed around the leg of a patient.Surgical techniques are also employed in which valves can be bypassed orreplaced with autologous sections of veins with competent valves.

Minimally invasive techniques and instruments for placement ofintraluminal medical devices have developed over recent years. A widevariety of treatment devices that utilize minimally invasive technologyhas been developed and includes stents, stent grafts, occlusion devices,infusion catheters and the like. Minimally invasive intravasculardevices have especially become popular with the introduction of coronarystents to the U.S. market in the early 1990's. Coronary and peripheralstents have been proven to provide a superior means of maintainingvessel patency, and have become widely accepted in the medicalcommunity. Furthermore, the use of stents has been extended to treataneurisms and to provide occlusion devices, among other uses.

Recently, prosthetic valves have been developed that use a support framesuch as a stent. Frequently, a graft member is attached to the supportframe and provides a valve function to the device. For example, thegraft member can be in the form of a leaflet that is attached to a stentand movable between first and second positions. In a first position, thevalve is open and allows fluid flow to proceed through a vessel in afirst direction, and in a second direction the valve is closed toprevent fluid flow in a second, opposite direction. An example of thistype of prosthetic valve is described in commonly owned U.S. Pat. No.6,508,833, to Pavcnik for a MULTIPLE-SIDED INTRALUMINAL MEDICAL DEVICE,which is hereby incorporated by reference in its entirety. In otherexamples of prosthetic valves, a tube that terminates in leaflets isattached to one or more support frames to form a valve. The leafletsopen to permit fluid flow in a first direction in response to fluidpressure on one side of the leaflets, and close to prevent fluid flow ina second, opposite direction in response to fluid pressure on oppositesides of the leaflets. An example of this configuration is provided inU.S. Pat. No. 6,494,909 to Greenhalgh for AN ENDOVASCULAR VALVE, whichis hereby incorporated by reference in its entirety.

Prosthetic valves are designed to replace or supplement the function ofincompetent natural valves. The use of an expandable support frame invalve devices allows for the use of minimally invasive delivery devicesand techniques for placement of the valves within body vessels, whichwill likely lower the overall cost of treatment and increase theacceptance of these medical devices by practitioners and patients alike.

The inclusion of a support frame and a valve member, such as a graftmember, in a prosthetic valve device necessarily requires a connectionbetween these components. The dynamic environment in which prostheticvalves are placed requires a connection that minimizes migration of thegraft member on the support frame.

SUMMARY OF THE INVENTION

In some embodiments, the invention provides intraluminal medical devicesthat include structural features adapted to enable a more stableconnection between the graft member and the support frame. Thus, theinvention provides implantable medical devices that include a graftmember attached to a support frame that defines structural features thatenable a more stable connection between the graft member and the supportframe. In exemplary embodiments, medical devices according to theinvention provide a valve for regulating fluid flow through a bodyvessel. The device is particularly well suited for percutaneous deliverythrough a body vessel to a point of treatment, and comprises aprosthetic venous valve in an illustrative embodiment.

The prosthetic venous valves according to the invention include asupport frame, such as an endoluminal stent, that has radiallycompressed and radially expanded configurations. The support frame cancomprise any suitable support frame, including self expandable, balloonexpandable, wire, tube, metal, polymeric, composite, and other types ofsupport frames known in the art. The devices also include at least onegraft member attached to the support frame. The graft member preferablyprovides a valve function to the device. In exemplary embodiments, thegraft member comprises a valve leaflet that moves between first andsecond positions while remaining attached to the support frame. In thefirst position, the leaflet substantially blocks the lumen of thevessel, while the lumen is substantially open when the leaflet is in thesecond position. Thus, the leaflet permits fluid flow through the vesselin a first direction when in the first position, and substantiallyprevents fluid flow in a second, opposite direction when in the secondposition. The graft member can also be formed into other suitable valveconfigurations, such as a duckbill configuration, a tube or partial tubeconfiguration, and an evertable tube configuration. The graft member canbe formed of any suitable material, including natural and syntheticmaterials. In exemplary embodiments of the invention, the graft memberis formed of an Extracellular Matrix (ECM) material, such as SmallIntestine Submucosa (SIS).

The graft member can be attached to the support frame in a variety ofways, such as by sutures or other suitable attachment elements. Inexemplary embodiments, the support frame defines one or more structuralfeatures that provide a securement position at which the graft membercan be attached to the support frame. Preferably, the structural featureis adapted to prevent migration of the graft material relative to thesupport frame. The type of structural feature utilized depends on thetype of support frame used. For example, when a wire support frame isutilized, a loop or eyelet structure can be formed readily in the wireof the support frame. The loop or eyelet can be used as a securementposition at which the graft member can be attached to the support frameby an attachment element. If, however, a tube member is used as thesupport frame, such as a stent cut from a solid tube of material, theformation of loops and eyelets may be difficult. Accordingly, otherstructural features, such as contoured struts, areas of enlarged width,barbs formed on the struts, strut projections, clips, and otherstructures can be used. Also, various attachment techniques, eitheralone or in combination with the various structural features, can beutilized for attaching the graft member to the support frame.

In other embodiments, the graft member is adhered to itself or to thesupport frame with agents such as tissue adhesives, cross-linkers, ornatural materials such as fibrin. Also, techniques such as laser weldingcan be used. Furthermore, the graft member itself can define structuralfeatures that facilitate attachment to a support frame, such as a taband corresponding slot.

A more detailed explanation of the invention is provided by the attacheddrawings and detailed description, which illustrate exemplaryembodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top view of a support frame for use in medical devicesaccording to the invention.

FIG. 1 a is an enlarged partial cross sectional view of the supportframe illustrated in FIG. 1.

FIG. 2 is a perspective view of the support frame of FIG. 1 deployedinside a body vessel.

FIG. 3 is a top view of a prosthetic venous valve according to a firstexemplary embodiment of the invention.

FIG. 4 is an enlarged partial view of the prosthetic venous valveillustrated in FIG. 3.

FIG. 5 is a perspective view of a support frame for use in medicaldevices according to the invention.

FIG. 6 is a perspective view of the support frame illustrated in FIG. 5in a radially compressed configuration.

FIG. 7 is a partial view of a contoured strut for use in a medicaldevice according to one embodiment of the invention.

FIG. 8 is a partial view of a contoured strut for use in a medicaldevice according to another embodiment of the invention.

FIG. 9 is a partial view of a contoured strut for use in a medicaldevice according to another embodiment of the invention.

FIG. 10 is a partial view of a contoured strut for use in a medicaldevice according to another embodiment of the invention.

FIG. 11 is a partial view of a contoured strut having an area ofincreased width for use in a medical device according to anotherembodiment of the invention.

FIG. 12 is a partial view of a contoured strut defining projections foruse in a medical device according to another embodiment of theinvention.

FIG. 13 is a partial view of a support frame for use in a medical deviceaccording to another embodiment of the invention.

FIG. 14 is an enlarged partial view of the support frame illustrated inFIG. 13.

FIG. 15 is a top view of a support frame for use in medical devicesaccording to another embodiment of the invention.

FIG. 16 is a perspective view of a medical device according to theinvention positioned within a body vessel.

FIG. 17 is a partial cross-sectional view taken along line a-a in FIG.16.

FIG. 18 is a schematic illustration of one configuration of barbs on astrut according to an embodiment of the invention.

FIG. 19 is a schematic illustration of one configuration of barbs on astrut according to another embodiment of the invention.

FIG. 20 is a schematic illustration of one configuration of barbs on astrut according to another embodiment of the invention.

FIG. 21 is a partial cross-sectional view of a medical device accordingto another embodiment of the invention.

FIG. 22 a is a schematic illustration of the fabrication of the medicaldevice illustrated in FIG. 21.

FIG. 22 b is a schematic illustration of the fabrication of the medicaldevice illustrated in FIG. 21.

FIG. 22 c is a schematic illustration of the fabrication of the medicaldevice illustrated in FIG. 21.

FIG. 23 is a partial cross-sectional view of a medical device accordingto an embodiment of the invention.

FIG. 24 is a partial cross-sectional view of a medical device accordingto another embodiment of the invention.

FIG. 25 is a partial cross-sectional view of a medical device accordingto another embodiment of the invention.

FIG. 26 is a partial cross-sectional view of a medical device accordingto another embodiment of the invention.

FIG. 27 is a partial cross-sectional view of a medical device accordingto another embodiment of the invention.

FIG. 28 is a partial cross-sectional view of a medical device accordingto another embodiment of the invention.

FIG. 29 is a partial view of a medical device according to anotherembodiment of the invention.

FIG. 30 is a top view of a medical device according to anotherembodiment of the invention.

FIG. 31 is a partial view of a medical device according to anotherembodiment of the invention.

FIG. 32 is an enlarged partial view of a medical device according toanother embodiment of the invention.

FIG. 33 is a partial view of a medical device according to anotherembodiment of the invention.

FIG. 34 is a partial view of a medical device according to anotherembodiment of the invention.

FIG. 35 is a partial view of a medical device according to anotherembodiment of the invention.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS OF THE INVENTION

The following provides a detailed description of currently exemplaryembodiments of the invention. The description is not intended to limitthe invention in any manner, but rather serves to enable those skilledin the art to make and use the invention.

A medical device according to the invention provides a support framewith an attached graft member. Exemplary embodiments of the inventionprovide a valve for regulating fluid flow through a body vessel. Medicaldevices according to these embodiments include a support frame and agraft member that imparts a valve function to the device.

The support frame provides an attachment member for the graft member. Awide variety of support frames are known in the art, and any suitablesupport frame can be utilized. The support frame can also provide astenting function, i.e., exert a radially outward force on the interiorvessel wall, although this function is not necessary and is consideredoptional. By including a support frame having stenting properties, themedical devices of the invention can provide both a stenting and avalving function at a point of treatment.

The stent art provides numerous support frames acceptable for use in theinvention, and any suitable stent can be used. The support frame needonly provide the desired attachment member for the graft member. Thespecific support frame chosen will depend on numerous factors, includingthe vessel in which the device is being implanted, the axial length ofthe treatment site, the number of valves desired in the support frame,the inner diameter of the vessel, the delivery method for placing thesupport frame and valve, and others. Those skilled in the art candetermine an appropriate support frame based on these and other factors.

The support frame can be either self-expandable or balloon expandable. Aballoon expandable support frame may provide advantage to treatmentsites where greater radial strength is desired. Self-expandable stentsprovide a relatively simple deployment at the point of treatment.Suitable support frames can also have a variety of configurations,including braided strands, helically wound strands, ring members,consecutively attached ring members, tube members, and frames cut fromsolid tubes.

Suitable support frames can be made from a variety of materials, andneed only be biocompatible, or able to be made biocompatible, andprovide the desired stenting function, if appropriate. Examples ofsuitable materials include, without limitation, stainless steel, nickeltitanium (NiTi) alloys, e.g., nitinol, other shape memory and/orsuperelastic materials, cobalt-chromium alloys, natural and syntheticpolymers, and composite materials. Examples of suitable polymericmaterials include polypropylenes and polyethylenes. A resorbablematerial can also be use for the support frame. As used herein, the term“resorbable” refers to the ability of a material to be absorbed into atissue and/or body fluid upon contact with the tissue and/or body fluid.A number of resorbable materials are known in the art, and any suitableresorbable material can be used. Examples of suitable types ofresorbable materials include resorbable homopolymers, copolymers, orblends of resorbable polymers. Specific examples of suitable resorbablematerials include poly-alpha hydroxy acids such as polylactic acid,polylactide, polyglycolic acid (PGA), or polyglycolide; trimethlyenecarbonate; polycaprolactone; poly-beta hydroxy acids such aspolyhydroxybutyrate or polyhydroxyvalerate; or other polymers such aspolyphosphazines, polyorganophosphazines, polyanhydrides,polyesteramides, polyorthoesters, polyethylene oxide, polyester-ethers(e.g., polydioxanone) or polyamino acids (e.g., poly-L-glutamic acid orpoly-L-lysine). There are also a number of naturally derived resorbablepolymers that may be suitable, including modified polysaccharides, suchas cellulose, chitin, and dextran, and modified proteins, such as fibrinand casein.

Stainless steel and nitinol are currently considered desirable materialsfor use in the support frame due at least to their biocompatibility,shapeability, and well-characterized nature.

Examples of suitable support frames for use in medical devices accordingto the invention include those described in U.S. Pat. No. 6,464,720 toBoatman et al. for a RADIALLY EXPANDABLE STENT; U.S. Pat. No. 6,231,598to Berry et al. for a RADIALLY EXPANDABLE STENT; U.S. Pat. No. 6,299,635to Frantzen for a RADIALLY EXPANDABLE NON-AXIALLY CONTRACTING SURGICALSTENT; U.S. Pat. No. 4,580,568 to Gianturco for a PERCUTANEOUSENDOVASCULAR STENT AND METHOD FOR INSERTION THEREOF; and publishedUnited States patent application 2001/0039450 to Pavcnik et al. for anIMPLANTABLE MEDICAL DEVICE, all of which are hereby incorporated byreference in their entirety.

In some embodiments of the invention, a support frame formed from wireis utilized. FIG. 1 illustrates a suitable wire support frame 10 for usein a medical device according to the invention. This support frame 10 isexemplary of suitable support frames that can be modified to include theinvention. Support frame 10 is described in detail in U.S. Pat. No.6,508,833 to Pavcnik et al. for a MULTIPLE-SIDED INTRALUMINAL MEDICALDEVICE, which is hereby incorporated by reference in its entirety. Thesupport frame 10 is made of resilient material, preferably metal wireformed from stainless steel or a superelastic alloy, such as nitinol.While round wire is depicted in the figure, other wire types, e.g.,flat, square, triangular, D-shaped, delta-shaped, etc. may be used toform the frame. In the illustrative embodiment, the frame 10 comprises aclosed circumference of a single piece of material that is formed into adevice having a plurality of sides 12 interconnected by a series ofbends 14, 16, 18, 20. The depicted embodiment includes four sides 12 ofapproximately equal length. Alternative embodiments include forming aframe into any polygonal shape, for example, a pentagon, hexagon,octagon, etc. In the embodiment of FIG. 1, each of the bends 14, 16, 18,20 interconnecting the sides 13 comprise a coil 14 of approximately oneand a quarter turns. Alternative bend embodiments includeoutward-projecting fillets and inward-projecting fillets comprising aseries of curves. Fillets are well known in the stent art as a means toreduce stresses in bends. When using stainless steel wire, the size ofthe wire which should be selected depends on the size of device and theapplication. Wire that is too stiff can damage the vessel, not conformwell to the vessel wall, and increase the profile of the device whenloaded in the delivery system prior to deployment.

The single piece of material comprising the frame 10 is formed into theclosed circumference by securing the first and second ends 24, 26 withan attachment mechanism 28 such as a piece of metal cannula (see FIG.1A). The ends 24, 26 of the single piece are inserted into the cannula28 and secured with solder 30, a weld, adhesive, or crimping to form theclosed frame 10. The ends 24, 26 of the single piece can be joineddirectly without addition of a cannula 28, such as by soldering,welding, or other methods to join ends 24, 26. Besides joining the wire,the frame could be fabricated as a single piece of material, by stampingor cutting the frame 10 from another sheet (e.g., with a laser),fabricating from a mold, or some similar method of producing a unitaryframe.

The support frame 10 depicted in FIG. 1 is shown in a firstconfiguration 25 whereby all four bends 14, 16, 18, 20 and each of thesides 12 generally lie within a single flat plane. To resilientlyreshape the frame 10 into a second configuration 35, shown in FIG. 2,the frame 10 of FIG. 1 is folded twice, first along one diagonal axis 32with opposite bends 16 and 20 being brought into closer proximity,followed by opposite bends 14 and 18 being folded toward one another andbrought into closer proximity. The second configuration 35, depicted inFIG. 2, has two opposite bends oriented at the first end 32 of the frame10, while the other opposite bends 16, 20 are oriented at the second end34 of the frame 10 and rotated approximately 90° with respect to bends14 and 18 when viewed in cross-section. The medical device in the secondconfiguration 35 can be used as a stent to maintain an open lumen 36 ina vessel 38, such as a vein, artery, or duct. The bending stressesintroduced to the frame 10 by the first and second folds required toform the second configuration 35 apply force radially outward againstthe vessel wall 40 to hold the frame 10 in place and prevent vesselclosure. Absent any significant plastic deformation occurring duringfolding and deployment, the second configuration 35, when not in thevessel or subject to other constraining means, will at least partiallyreturn to the first configuration 25, although some deformation canoccur depending on the material used. It is also possible to plasticallydeform the frame 10 into the second configuration 35, such that it doesnot unfold when restraint is removed. This might be particularly desiredif the device is made from nitinol or a superelastic alloy.

FIG. 3 illustrates a medical device 100 formed from a wire support frame110 configured into a diamond shape 112. A graft member 114 is attachedto the support frame 110 and has two leaflets 116, 118 that define acentral opening 120. The graft member 114 is attached to the supportframe 110 by attachment elements 122. As used herein, the term“attachment element” refers to any member that can be used to form aconnection between a support frame and a graft member. Examples ofsuitable attachment elements include, without limitation, sutures,coils, wires, clips, rings, and other suitable members. The attachmentelement can comprise a separate member or can be integrally formed bythe support frame or graft member. The specific attachment elementchosen for a particular embodiment of the invention will depend onvarious considerations, including the type and configuration of thesupport frame and/or graft member.

Similar to the embodiment illustrated in FIGS. 1 and 2, the supportframe 110 illustrated in FIG. 3 includes bends 124, 126, 128 and 130that each comprise a coil 132. The coil 132 provides an eyeletconfiguration in the support frame 110. As such, the coil 132 defines astructural feature in the support frame 110 to which the graft member114 can be attached.

FIG. 4 illustrates a magnified view of a coil 132 in the device 100illustrated in FIG. 3. As illustrated in FIG. 4, the graft member 114has a notch area that receives the coil 132 and allows for the placementof attachment elements 122 around the portion of the support frame 110in the coil 132 and through the adjacent graft member 114. In thisconfiguration, the coil 132 provides an additional attachment point forthe graft member 114. The graft member 114 is not able to migrate alongthe support frame 110 near the position of the coil 132 because theoverlap region 134 blocks the attachment elements 122 from travelingalong the support frame 110. The overlap region 134 is a length alongthe support frame 110 that includes at least two thicknesses of the wiremember that forms the support frame 110. To further prevent migration inthis area, the two portions of the support frame 110 that overlap in theoverlap region 134 can be joined together by various means, such asplacement of an attachment element at the overlapping portions.

FIGS. 5 and 6 illustrate a second type of support frame 210 suitable foruse in medical devices according to the invention. Support frame 210 isdescribed in detail in U.S. Pat. No. 6,299,635, to Frantzen. The supportframe 210 comprises a unitary member cut from a solid piece of metaltubing, such as by laser cutting. A variety of unitary support framescut from tubes are known to those skilled in the art. Any suitablesupport frame of this type can be utilized in the invention. Generally,these support frames, such as the support frame 210 illustrated in FIG.5, include a plurality of struts 212 of the tube material left after thecutting process. A plurality of open spaces 214 is formed by the removalof the material between the struts 212.

A variety of configurations of the struts 212 and open spaces 214 can beutilized. The configuration chosen will depend on numerous factors,including the size of the vessel, the desired radial strength of thestent, and the desired longitudinal flexibility of the stent. Also, aswill be described more fully below, the struts 212 can be configured ina variety of manners in accordance with the invention to provide thedesired attachment of the graft member to the support frame 210.

Similar to the support frame illustrated in FIGS. 1 and 2, the supportframe 210 has both a radially expanded and radially compressedconfiguration. FIG. 6 illustrates the radially compressed configurationof the support frame 210. As best illustrated in FIG. 6, the open spaces214 are reduced in size when the support frame is in the radiallycompressed configuration. Support frames cut from tube members, such asthe frame 210 illustrated in FIGS. 5 and 6, are typically balloonexpandable support frames.

Medical devices according to the invention include a support frame and agraft member. The graft member can be attached to the support frame in avariety of configurations. Also, the support can define structuralfeatures that are adapted to substantially prevent movement of the graftmember along the struts of the support frame.

In a first series of embodiments of the invention, struts of the supportframe are contoured to provide at least one non-linear segment acrosswhich a graft member can be attached. FIGS. 7 through 10 illustrateportions of medical devices in accordance with this first series ofembodiments.

FIG. 7 illustrates a portion of a medical device 300 according to anembodiment of the invention. In this embodiment, a strut 310 defines aserpentine path 312 that includes a plurality of non-linear segments314. The serpentine path 312 is defined by a single strut 310, and doesnot include any bend or other transition to another strut. FIG. 35illustrates an alternate embodiment in which one strut 1800 defines astructural feature, such as enlarged region 1802, that cooperates withone or more other struts 1804, 1806 to prevent migration of anattachment element 1808 that attaches a graft member 1810 to the strut1800. In the embodiment illustrated in FIG. 7, the graft member 316 issecured to the strut 310 by two or more attachment elements 318 thatsurround a circumference of the strut 310 and extend through the graftmember 316. The graft member 316 is a sheet of material and an edge 317of the graft member 316 is in contact with a surface of the strut 310.This contact can be an abutting relationship. As illustrated in the FIG.7, an attachment element 318 can be disposed on each side of anon-linear segment 314 along the strut 310. In the illustratedembodiment, a series of attachment elements 318 are secured to the strut310 and graft member 316 along a series of non-linear segments 314 onthe strut 310. In this configuration, the graft member 316 issubstantially prevented from migrating due to the curvilinear path thatwould need to be traveled by the attachment elements 318 for suchmigration to occur.

Any suitable graft member can be used in medical devices according tothe invention. The graft member can comprise any suitable material forimplantation in a body vessel. The graft member need only bebiocompatible or be able to be made biocompatible. Examples of suitablematerials for the graft member include natural materials, syntheticmaterials, and combinations thereof. Examples of suitable naturalmaterials include ECMs, such as small intestine submucosa (SIS), andother bioremodellable materials, such as bovine pericardium. Otherexamples of ECM materials that can be used for the graft member includestomach submucosa, liver basement membrane, urinary bladder submucosa,tissue mucosa, and dura mater. Examples of suitable synthetic materialsinclude polymeric materials, such as expanded polytetrafluoroethyleneand polyurethane. ECMs are particularly well suited materials for use inthe graft member, at least because of their abilities to remodel andbecome incorporated into adjacent tissues. These materials can provide ascaffold onto which cellular in-growth can occur, eventually allowingthe material to remodel into a structure of host cells.

FIG. 8 illustrates a portion of medical device 400 according to anotherembodiment of the invention. In this embodiment, the strut 410 defines aplurality of angulated linear segments 412. The attachment elements 414are preferably disposed across these angulated segments. Similar to theembodiment illustrated in FIG. 7, an edge 417 of the graft member 416 isin contact with a surface of the strut 410. In this embodiment, thegraft member 416 has one or more folds 418 that are substantiallycoaxial with a portion of the strut 410 and provide a point at which thegraft member 416 can be secured to the strut 410 by attachment element414.

FIG. 9 illustrates a portion of a medical device 500 according toanother embodiment of the invention. This embodiment is similar to thatillustrated in FIG. 8, except that the graft member 516 does not includefolds. Thus, the strut 510 includes a plurality of angulated linearsegments 512. A series of attachment elements 514 secure the graftmember 516 to the strut 510. Thus, as illustrated in FIG. 9, the graftmember 516 follows a substantially linear path. Also, an edge 517 of thegraft member is in contact with a surface of the strut 510.

FIG. 10 illustrates a portion of a medical device 600 according toanother embodiment of the invention. This embodiment is similar to theembodiment illustrated in FIG. 7, except as described below. The strut610 includes linear portions 612 disposed between adjacent curvilinearsegments 614. The linear segment 612 provides an area for attachment ofattachment elements 616 to the strut 610. As illustrated in FIG. 10, thecurvilinear portions 614 are disposed between two linear segments 612and provide a structural feature that substantially prevents sliding ofattachment elements 616 along the strut 610. An edge 617 of the graftmember 618 is in contact with a surface of the strut 610.

FIG. 11 illustrates a portion of a medical device 700 according toanother embodiment of the invention. In this embodiment, the strut 710includes a portion 712 having an increased width w2. The width w2 of thearea 712 is greater than the width w1 of at least one other portion ofthe strut 710. As used herein, the term “width” refers to any dimensionof a strut other than length, and includes a width of a substantiallytwo dimensional strut, a thickness of a three dimensional strut, and adiameter of a strut with a substantially circular cross-sectional shape.As illustrated in FIG. 11, a portion 712 having an increased width w2 isdisposed between two portions 714 of a lesser width, such as width w1.Attachment elements 716 are disposed around a circumference of the strut710 and through the graft member 718 at a position on the strut betweenportions 712 and 714. The attachment elements 716 are drawn tight to thecircumference of the strut 710 at these locations. Consequently, eachattachment element 716 is substantially prevented from migrating towardsan adjacent portion 712 of increased width w2. When two attachmentelements 716 are disposed on either side of portion 712 of increasedwidth w2, the prevention of migration is effective in both directionsbecause migration of one attachment element 716 towards an adjacentportion 714 of lesser width w1 necessarily involves migration of theother attachment element 716 towards the portion of increased width w2,which is prevented due to the taught nature of the connection betweenthe attachment element 716 and the strut 710. An edge 717 of the graftmember 718 is in contact with a surface of the strut 710.

FIG. 12 illustrates a portion of a device 800 according to anotherembodiment of the invention. In this embodiment, the strut 810 definesone or more projections 812. Attachment elements 814 are placed across acircumference of the strut 810 and through the graft member 816,adjacent one or more projections 812. An edge 817 of the graft member818 is in contact with a surface of the strut 710. The projections 812define stops that prevent migration of the attachment element 814 alongthe length of the strut 810. The projections 812 can take a variety offorms, including the barb like forms illustrated in FIG. 12, as well asbumps, nibs, and rings. Furthermore, the projections 812 can be definedby the strut 810, or alternatively can comprise separate membersattached to the strut 810.

FIG. 12 illustrates three configurations of the projections 812 on thestrut 810. For example, at the upper portion of FIG. 12, the strut 810includes a single projection 812. The attachment element 814 is disposedadjacent the projection 812. In the middle portion of FIG. 12, twoprojections 812 are placed on a single side of the strut 810. Anattachment element 814 is disposed between the projections 812. Thisconfiguration effectively captures the attachment element 814 betweenthe projections 812. In the lower portion of FIG. 12, two projections812 are disposed on opposite sides of the strut 810. The attachmentelement 814 is disposed between the opposing projections 812. In thisconfiguration, the projections 812 define stops on each side of theattachment element 814. In medical devices according to the invention, avariety of these configurations can be used either exclusively or in anysuitable combination with one another. Furthermore, as illustrated inFIG. 12, attachment elements 814 can be disposed across the strut 810 inareas that do not include any projections 812. The use of one or severalprojections 812 along the length of the strut 810 substantially preventsmigration of the graft member 816 along the strut 810.

FIGS. 13 and 14 illustrate a support frame 900 suitable for use inmedical devices according to the invention. In this embodiment, thesupport frame 900 defines one or more barbs 902 along its length. Asillustrated in the enlarged partial view shown in FIG. 14, the barbs 902preferably comprise pointed members extended away from the surface ofthe support frame 900. The pointed configuration of the barb 902 allowsfor piercing through an attached graft member. Each barb 902 can beformed from a portion of the material of the support frame 900, as shownin FIG. 14, or can comprise a separately attached member.

As best illustrated in FIG. 13, the barbs 902 at a first end 906 of thesupport frame 900 can extend in a first direction, and the barbs 902 ata second end 908 of the support frame 900 can extend in a seconddirection. This configuration is particularly well suited for supportframes, such as the frame 900 illustrated in FIG. 13, in which the twoopposing ends are brought near each other when the device is positionedwithin a vessel. When the two ends are brought near each other, allbarbs 902 extend in the same direction, providing effective resistanceto migration of an attached graft member in the opposite direction.

In some applications, medical devices according to the invention will beexposed to flow that occurs in both directions at different times. Forexample, prosthetic venous valves are exposed to both antigrade andretrograde flow continually over time. Thus, it may be desirable toprovide resistance to migration of an attached graft member in bothdirections. FIG. 15 illustrates a support frame 1000 that includes avariety of barbs extending from its surface 1002. At a first end 1004 ofthe support frame 1000, a first series of barbs 1006 extend in a firstdirection, and a second series of barbs 1008 extend in a second,different direction, which can be a substantially opposite direction.Likewise, at a second end 1010 of the support frame, a first series ofbarbs 1012 extend in a first direction and a second series of barbs 1014extend in a second, different direction. As discussed above, all of thebarbs preferably comprise pointed members extending away from thesurface of the support frame 1100.

The first series of barbs 1006 at the first end 1004 and the firstseries of barbs 1012 at the second end 1010 resist migration of anattached graft member 1016 in a first direction 1018, as illustrated inFIG. 16, when the device is deployed in a vessel 1020. The second seriesof barbs 1008 at the first end 1004 and the second series of barbs 1014at the second end 1010 resist migration of the graft member 1016 in asecond, different direction 1024. Thus, the support frame 1000substantially prevents migration of the graft member 1016 along thesupport frame 1000 in two different directions.

FIG. 17 illustrates a cross-sectional view of a barb 1030 extendingthrough the graft member 1016. By extending through the graft member1016, the barb 1030 substantially prevents migration of the graft member1016 along the support frame.

FIGS. 18 and 19 illustrate alternative configurations for barbs onsupport frame 1000. In FIGS. 18 and 19, opposing barbs 1030, 1030′ arearranged on one side of support frame 1000. These configurations areparticularly well-suited for use in medical devices composed of flatstock or nearly flat material.

FIG. 20 illustrates an alternative embodiment for positioning of thebarbs on the support frame. In this embodiment, barbs 1040, 1040′ arepositioned on different sides of the support frame 1000. This is incontrast to the embodiments illustrated in FIGS. 13-19 in which thebarbs are positioned on a single side of the support frame.

FIG. 21 illustrates a portion of a medical device 1100 according toanother embodiment of the invention. In this embodiment, the supportframe 1102 defines a plurality of projections 1104 that extend throughthe thickness of the graft member 1106 and along a portion of a lengthof the graft member 1106. In this configuration, the projections 1104provide additional securement of the graft member 1106 to the frame byeffectively clamping the graft member 1106 to the frame 1102.

FIGS. 22 a, 22 b, and 22 c provide schematic illustrations of afabrication process for the device 1100 illustrated in FIG. 21. First,as illustrated in FIG. 22 a, a support frame 1102 includes an upstandingprojection 1104. A section of graft material 1106 defining an opening1108 is placed on the support frame 1102 such that the upstandingprojection 1104 is passed through the opening 1108. FIG. 22 billustrates the intermediate product in which the graft member 1106 ispositioned on the support frame 1102 and the upstanding projection 1104extends through the opening 1108. Next, the upstanding projection 1104is bent over a portion of the graft member 1106 so that a portion of theprojection 1104 extends along a portion of a length of the graft member1106. The graft member 1106 can be further secured to the support frame1102 by clamping or crimping the projection 1104 against the graftmember 1106 and support frame 1102, effectively capturing the graftmember 1106.

FIGS. 23 through 27 illustrate portions of medical devices according toembodiments of the invention. In these embodiments, a strut 1200 definesone or more projections that define a stop for an attachment element1202. The projections of these embodiments are similar to thoseillustrated in FIG. 12 and described above, except as detailed below.

FIGS. 23 through 26 illustrate various projections that are suitable foruse when it is desirable to attach a graft member 1204 to a portion of asupport frame in a manner that the graft member 1204 extendssubstantially coplanar with the strut 1200. Also, an edge 1205 of thegraft member 1204 is in contact with a surface of the strut 1200. Thiscontact can be an abutting relationship. In FIG. 23, two projections1206, 1208 surround a single attachment element 1202. Each of theprojections 1206, 1208 define an enlarged region of the strut 1200having a width w2 that is greater than a width w1 of a non-enlargedregion of the strut 1200. This configuration essentially captures theattachment element 1202 between the enlarged regions 1206, 1208, therebypreventing migration of the graft member 1204 along the strut 1200. FIG.24 illustrates a first alternative configuration of projections 1206′,1208′. In this configuration, the cross-sectional shape of theprojections 1206′, 1208′ each comprise a substantially triangular shapedregion defined by the strut 1200. FIG. 25 illustrates anotheralternative configuration of the projections 1206″, 1208″. In thisembodiment, each of the barbs 1206″, 1208″ comprise a square orrectangular cross-sectional shaped area of the strut 1200. Theprojections 1206″, 1208″ extend outward from at least two sides of thestrut 1200. In FIG. 26, the projections 1206″′, 1208″′ also comprisesquare or rectangular cross-sectional shaped areas of the strut 1200. Inthis embodiment, however, the enlarged regions 1206″, 1208″ extendoutward from only one side of the strut 1200. Each of these describedconfigurations may provide advantages in manufacturing of support framesor in assembly of the device in which the graft member 1204 is securedto the strut 1200.

As described above, the embodiments illustrated in FIGS. 23 through 26provide projections that are suitable for use when it is desirable toextend the graft member coplanar with a strut. In some devices, however,it may be desirable to extend the graft member at an angle with respectto a strut. FIG. 27 illustrates a strut 1300 that defines a projection1302 that is suitable for this purpose. As illustrated in the figure,the projection 1302 comprises a first region 1304 that extends away fromone side of the strut 1300 in a first direction, and a second region1306 that extends away from a second side of the strut 1300 in a seconddirection. As illustrated in FIG. 27, the regions 1304, 1306advantageously have triangular cross-sectional shapes that aresubstantially opposite in arrangement relative to one another. Theattachment element 1308 is disposed across the projection 1302 andthrough the graft member 1310. The projection 1302 formed by the regions1304, 1306 allows for placement of the attachment element 1308 at anangle to a lengthwise axis of the strut 1300, thereby allowing the graftmember 1310 to be positioned at an angle with respect to the strut 1300.Also, an edge 1311 of the graft member 1310 is in contact with a surfaceof the strut 1300, and can be in an abutting relationship with the strut1300. It is noted that a combination of the various projections can beused in medical devices according to the invention. For example, in asingle medical device, it may be desirable to have a graft extendcoplanar with a strut in one portion of the device, in which aprojection such as those illustrated in FIGS. 23 through 26 would beappropriate, while having a graft member extend at an angle with respectto a strut in another portion of the device, in which a projection, suchas that illustrated in FIG. 27, would be appropriate. A desirablenumber, configuration, and placement of the various projections used canbe determined for a particular support frame in a medical deviceaccording to the invention.

FIG. 28 illustrates a cross-sectional view of a portion of a medicaldevice 1400 according to another embodiment of the invention. In thisembodiment, a clip member 1402 is disposed around the graft member 1404to form a snug fit between the graft member 1404 and strut 1406. Theclip member 1402 is a suitable attachment element for use in embodimentsof the invention. The clip member 1402 retains the graft member 1404 onthe strut 1406 by this snug fit. The clip member 1402 is preferablyformed of a resilient material and is force fit over the graft member1404 and strut 1406. The clip member 1402 can take a variety ofconfigurations. A C-shaped clip member 1402, such as that illustrated inFIG. 28, provides an opening 1408 through which the graft member 1404and strut 1406 can be passed, while still retaining the desired snugfit. Once the clip member 1402 is positioned over the graft member 1404and strut 1406, the clip member 1402 retains the graft member 1404adjacent the strut 1406 by the frictional engagement of the snug fit,preventing migration of the graft member 1404 along the length of thestrut 1406. Multiple clip members 1402 can be arranged at variouspositions on a medical device according to the invention. Also, variousconfigurations, such as various lengths, of clip members 1402 can beused. The specific number and configuration of clip members 1402 used inany particular device will depend on various factors, such as the sizeof the device and the desired degree of interference fit between thestrut 1406 and the graft member 1404.

To further enhance the connection between the graft member 1404 andstrut 1406, additional securement means can be utilized in conjunctionwith the clip member 1402, such as another attachment element around acircumference of the strut 1406 and through the graft member 1404, aswell as other securement means such as an adhesive disposed between thegraft member 1404 and strut 1406.

Various configurations of attachment elements can be utilized to attachthe graft member to the support frame. For example, FIGS. 29 through 31illustrate various suitable arrangements that utilize sutures as theattachment elements. It is understood that other suitable attachmentelements can be used in these arrangements. In FIG. 29, two individualattachment elements 1502, 1504 are passed through the graft member 1506and around individual leg struts 1510, 1512. Also, each attachmentelement 1502, 1504 is tied around connecting strut 1514 that joins legstruts 1510, 1512. The embodiment illustrated in FIG. 30 is identical tothat in FIG. 29, except that the attachment elements are tied around ajunction area 1516 of connecting strut 1514 and the leg struts 1510,1512. In FIG. 31, an embodiment identical to that in FIG. 29 isillustrated, except that this embodiment uses a single attachmentelement 1518, with portions 1520 and 1522. The use of a singleattachment element 1518 eliminates one knot in the attachment element.

FIG. 32 illustrates a portion of a medical device 1600 according to anembodiment of the invention. In this embodiment, strut 1602 defines anaperture 1604. An attachment element 1606 is passed through the graftmember 1608, around the leg struts 1616, 1612, and through the aperture1606. This attachment element arrangement in combination with thestructural feature of the aperture 1606 substantially prevents migrationof the graft member 1608 along the leg struts 1610, 1612.

FIGS. 33 and 34 illustrate portions of a medical device 1700 accordingto another embodiment of the invention. In this embodiment, the strut1702 defines a barb that extends away from the strut 1702. An attachmentelement 1708 secures the graft member 1706 to the strut 1702, and ispassed behind the barb. The length y of the barb prevents the attachmentelement 1708 from separating from the barb as the length is greater thanthe slack present in the attachment element 1708, and therefore no knotis needed at the barb. The barb can comprise a member with one or morecurvilinear sides, such as barb 1704 illustrated in FIG. 33, or a memberwith one or more linear sides, such as barb 1704′ illustrated in FIG.34. No matter the configuration, the barb advantageously includes apoint 1710, which allows the barb to also provide an anchoring functionto the device.

As indicated above, some medical devices, such as venous valves, areexposed to fluid flow in two opposite directions once implanted in avessel. Accordingly, it may be necessary to include features that resistmigration of the graft member in the two directions. A combination ofone or more barbs disposed at one end of a device and an attachmentelement configuration or other feature described above can provide thedesired resistance to migration in two different directions.

The foregoing description includes the best mode for practicing theinvention. The description is intended only to aid in the understandingof the invention, and is not intended to limit the scope of theinvention in any manner.

1. An implantable medical device, comprising: an expandable supportframe having a first end, a second end, a surface, and a plurality ofstruts interconnected by bends; a first series of barbs disposed at thefirst end of the expandable support frame and extending in a firstdirection; a second series of barbs disposed at the second end of theexpandable support frame and extending in a second, different direction;and a graft member attached to the support frame; wherein each barb ofthe first and second series of barbs extends away from the surface ofthe expandable support frame and through the graft member.
 2. Theimplantable medical device according to claim 1, wherein the firstdirection is substantially opposite the second direction.
 3. Theimplantable medical device according to claim 1, wherein the expandablesupport frame is adapted such that the first and second ends of thesupport frame are brought near each other when the implantable medicaldevice is positioned within a vessel such that the barbs of the firstseries of barbs and the barbs of the second series of barbs extend inthe same direction.
 4. The implantable medical device according to claim1, further comprising a third series of barbs disposed at the first endof the expandable support frame and extending in a third direction thatis different than the first direction.
 5. The implantable medical deviceaccording to claim 4, wherein each barb of the third series of barbsextends away from the surface of the expandable support frame andthrough the graft member.
 6. The implantable medical device according toclaim 4, further comprising a fourth series of barbs disposed at thesecond end of the expandable support frame and extending in a fourthdirection that is different than the second direction.
 7. Theimplantable medical device according to claim 6, wherein each barb ofthe fourth series of barbs extends away from the surface of theexpandable support frame and through the graft member.
 8. Theimplantable medical device according to claim 1, wherein the expandablesupport frame is self-expandable.
 9. The implantable medical deviceaccording to claim 1, wherein the expandable support frame isballoon-expandable.
 10. The implantable medical device according toclaim 1, wherein the expandable support frame is formed from wire. 11.The implantable medical device according to claim 1, wherein theexpandable support frame is cut from a piece of tubing.
 12. Theimplantable medical device according to claim 1, wherein the expandablesupport frame is formed of one of a metal, a natural material, asynthetic material, a polymer, and a composite material.
 13. Theimplantable medical device according to claim 1, wherein the expandablesupport frame is formed of one of stainless steel, Nitinol and cobaltchromium.
 14. The implantable medical device according to claim 1,wherein the expandable support frame is formed of a resorbable material.15. The implantable medical device according to claim 1, wherein thegraft member comprises a natural material.
 16. The implantable medicaldevice according to claim 1, wherein the graft member comprises abioremodellable material.
 17. The implantable medical device accordingto claim 16, wherein the bioremodellable material comprises anextracellular matrix material.
 18. The implantable medical deviceaccording to claim 16, wherein the bioremodellable material comprisessmall intestine submucosa.
 19. The implantable medical device accordingto claim 1, wherein the graft member comprises a synthetic material. 20.The implantable medical device according to claim 1, wherein the graftmember comprises first and second leaflets that define an opening. 21.The implantable medical device according to claim 1, wherein the surfaceof the expandable support frame has first and second sides and all barbsof the first and second series of barbs are disposed on the first side.22. The implantable medical device according to claim 1, wherein thesurface of the expandable support frame has first and second sides;wherein at least one barb of the first series of barbs is disposed onthe first side; and wherein at least one barb of the second series ofbarbs is disposed on the second side.
 23. The implantable medical deviceaccording to claim 1, wherein at least one barb is integrally formed bythe expandable support frame.
 24. The implantable medical deviceaccording to claim 1, wherein at least one barb comprises a separatemember attached to the expandable support frame.
 25. An implantablemedical device according to claim 1, wherein the graft member defines avalve for regulating fluid flow through the implantable medical device.26. An implantable medical device, comprising: an expandable supportframe having a first end, a second end, a surface, and a plurality ofstruts interconnected by bends; first and second opposing barbs disposedat the first end; third and fourth opposing barbs disposed at the secondend; a graft member attached to the support frame; wherein each of thebarbs extends away from the surface of the expandable support frame andthrough the graft member.
 27. An implantable medical device, comprising:an expandable support frame having a first end, a second end, a surface,and a plurality of struts interconnected by bends; first and secondbarbs disposed on a first strut of the plurality of struts and extendingaway from the surface in opposing directions; a graft member having anedge in contact with at least a portion of the surface of the firststrut; and an attachment element placed across the first strut andthrough the graft member; wherein the attachment element is disposedbetween the first and second barbs.